With some types of semiconductor devices such as microelectromechanical system (MEMS) devices, it is desirable to seal the device (e.g. hermetically) for the device to perform properly over time. For example, with some types of MEMS accelerometers and gyroscopes, it is desirable to seal the MEMS device to prevent contamination of the moving parts of the MEMS device during subsequent processes and use.
One method for sealing a MEMS device is to bond a cap wafer to the wafer that includes the MEMS device. The cap wafer and the device wafer form a cavity for the MEMS device. Some cap wafers may include a lead glass frit located around the cavity that bonds to the second wafer under pressure and temperature. Other cap wafers may be attached using an aluminum germanium (AlGe) eutectic material bond. While AlGe material bonds have many advantages, there can be a poor bond between the cap wafer and the device wafer when an anti-stiction coating is formed on the surfaces of the MEMS device wafer.
What is therefore needed is an improved technique for forming an AlGe eutectic bond to seal a semiconductor device having an anti-stiction coating.
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